JPH05280629A - Cone pulley type non-stage transmission - Google Patents

Abstract

PURPOSE: To prevent unnecessarily high pressure level of pressure medium due to a preload valve, when a load applied to a transmission is light. CONSTITUTION: A torque feeler 19 is arranged to an output shaft 2. A preload valve 18 is controlled according to a load applied to the transmission. At a heavy load time, the flow of the pressure medium is throttled further than in the case of a light load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conical pulley type continuously variable transmission particularly used for automobiles, which comprises two conical pulley pairs arranged on an input shaft and an output shaft, and on both conical pulleys. A transmission means circulating between the pairs, each conical pulley being non-rotatably connected to a shaft supporting said conical pulley, one conical pulley being associated with each shaft. Is also fixed in position in the direction, and the associated second conical pulley is configured as an axially slidable part of the axially fixed cylinder piston unit for pressing the transmission means against the cylinder piston unit. , For the purpose of adjusting and maintaining the gear ratio, pressure medium is supplied from four control edge type spools via the supply section.
A control edged spool adjustable by an adjusting device and having an outlet for the charged pressure medium,
An outflow conduit is connected to the outflow section and at least one torque feeler is arranged in the outflow conduit, the torque feeler being in one of the shafts of a transmission in a torque transmission path of the shaft. Is arranged to influence the pressure medium pressure in the cylinder piston unit in relation to the load, the torque feeler being hydraulically connected in series with an adjustable preload valve, The preload valve is of a type adapted to additionally influence the pressure medium pressure.

[0002]

2. Description of the Related Art A conical pulley type continuously variable transmission of this type is disclosed in, for example, German Patent No. 374319.
It is known based on specification No. 5. In this known conical pulley type continuously variable transmission, a preload valve is hydraulically provided after the torque feeler arranged on the input side. This preload valve has an additional effect on the pressure medium pressure exclusively in relation to the transmission gear ratio, in which case the pressure medium pressure increases as the gear ratio of input speed to output speed increases. , Will also increase.

This pressure medium pressure is supplied by a pump, in which case the power consumption of this pump is approximately proportional to the pressure medium pressure to be supplied by this pump if the discharge flow rate is constant. .. The power consumption required to operate the pump and the friction losses associated with the pressing forces in the winding transmission mechanism adversely affect the overall efficiency of the transmission, so keep the pressure level as low as possible in relation to load conditions. Is the goal. This is particularly important in partial load areas, that is, especially in vehicles with city traffic.

However, German Patent 3743
In the transmission disclosed in U.S. Pat. No. 195, due to the preload valve operating purely only in relation to the transmission ratio, the pressure medium pressure can be very high even when the load applied to the transmission is low. It turns out that it will be held high. This occurs particularly when the load is low but the gear ratio is large.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve a conical pulley type continuously variable transmission of the type described at the beginning,
It is an object of the present invention to provide a conical pulley continuously variable transmission in which the pressure medium pressure is not maintained at an unnecessarily high pressure level by the preload valve when the load applied to the transmission is low.

[0006]

In order to solve this problem, in the structure of the present invention, the torque feeler is arranged on the output shaft, and the preload valve is controlled in relation to the load applied to the transmission. As described above, when the load is increased, the pressure medium outflow is narrowed more than when the load is reduced.

[0007]

According to the present invention, the following advantages can be obtained based on such an arrangement form. That is, when the load applied to the transmission is low, the hydraulic basic pressure, which affects the efficiency of the transmission at partial load, can be kept very low, so that the power consumed by the pump is unnecessarily high. I won't.

Further, it is necessary to obtain a reliable torque transmission without slip between the input shaft and the output shaft.
Since the pressing force between the conical pulley pair and the transmission means remains at a low level, the friction loss is also small.

At the same time, on the basis of the fact that the torque feeler is arranged on the output shaft, the pressure medium pressure is controlled not only purely in relation to the load, but also in relation to the gear ratio. Is guaranteed.

In a preferred embodiment of the invention, the preload valve is hydraulically preceded by the torque feeler.
This allows the pressure medium to flow out of the torque feeler without pressure and, furthermore, with the tedious manufacturing connections, is not guided from the rotating torque feeler into a fixed conduit leading to the preload valve. Complete.

From an operational point of view, it is advantageous if the movement adjustment of the preload valve is carried out against the resistance associated with it. This resistance is
It enables a higher speed of movement adjustment of the preload valve than during load reduction. As a result, idling of the transmission means in the conical pulley pair is better prevented.

The resistor arrangement comprises a cylinder piston arrangement, the movable part of which is rigidly connected to the preload valve. Furthermore, the cylinder piston device has a volume filled with pressure medium, which volume is reduced when the load is increased and emptied via a fixed throttle and a check valve which is then opened. On the other hand, when the load is reduced, the pressure medium is enlarged, and the pressure medium is filled only through the fixed throttle. By discharging or filling the pressure medium with respect to the volume against the pressure medium pressure formed in the outflow portion of the four-control edge type spool, the response characteristic of the preload valve can be improved by the conical pulley type continuously variable transmission. Can be adapted to load conditions.

One possibility for providing a load-related control of the preload valve is to adjust it by means of a cam transmission which is associated with the accelerator pedal of the internal combustion engine which serves as a drive. Is.

A more advantageous possibility, however, is to control the preload valve by means of an electronic control unit. The electronic control unit forms the control instructions from the data of the internal combustion engine acting as a drive, as determined by the sensor or from another data which can be retrieved from the vehicle.

The electronic control unit may be a component of a central electronic control unit present in the vehicle.

The electronic controller of the preload valve may include a proportional valve. This proportional valve defines the hydraulic pressure that operates the preload valve.

In order to obtain a particularly quick response of the transmission to increased loads, the torque feeler is designed as a torque pump. Between the torque feeler and the cylinder piston unit is arranged a bypass conduit leading to a control valve in front of the torque feeler, which bypass conduit has a check valve. When the torque is suddenly increased, the pressure medium flows from the torque feeler into the cylinder piston unit through the check valve.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a conical pulley type continuously variable transmission having an input shaft 1 and an output shaft 2. A pair of conical pulleys 3 and 4 is mounted on both shafts. Between the pair of conical pulleys, the transmission means 5 circulates and the input shaft 1
Torque is transmitted to the output shaft 2. With respect to the conical pulley pairs, which are respectively connected non-rotatably to the shafts supporting the conical pulley pairs, each conical pulley pair 3,
4, the first conical pulley is axially fixed also in the axial direction, whereas the corresponding second conical pulley is axially fixed in the axial direction of the axially fixed cylinder piston units 6, 7 (only shown schematically). It is configured as a slidable portion. Via the cylinder piston unit, the transmission means is pressed and the gear ratio is adjusted and maintained.

The pressure medium required for this purpose is supplied to the cylinder piston units 6, 7 via the pressure medium conduits 8, 9. The amount and pressure of the pressure medium is controlled via a four-controlled spool 10. The four-controlled edge spool is adjustable by the adjusting device 11.

In the embodiment shown, the adjusting device 11 is embodied as a drive for a linear movement. This linear motion drive is controlled by a microprocessor 12 in front of it. This control can be performed in relation to the actual measured values for speed, gear ratio, drive speed, etc.

The pressure medium distributed to the cylinder piston units 6, 7 by the four-controlled edge spool 10 is supplied by a pump 13. This pump pumps the pressure medium from the reservoir 14.

The pressure medium used for adjusting and maintaining the gear ratio traverses the control gap of the four-control edged spool 10 and then via the outlets 15, 16 to the outlet conduit 17.
Flow into. Through this outlet conduit, the pressure medium is returned to the sump 14 via a preload valve 18 and a torque feeler 19. In this case, the pressure medium can also be used for the purpose of lubricating and cooling the transmission means 5 and the conical pulley pairs 3, 4.

On the basis of the throttling action of the preload valve 18 and the torque feeler 19, the basic pressure in the outflow conduit 17 is defined. This acts on the one hand on the pressing force of the cylinder piston units 6, 7 and on the other hand on the pressure medium pressure to be supplied by the pump 13.

The preload valve 18 has a piston 20, one end 21 of which is loaded with the pressure of the outflow conduit 17 and the other end of which is loaded with the spring force of a spring 22.

The spring force of the spring 22 is linked via the cam transmission 23 to the position of the accelerator pedal 24 of the internal combustion engine and is therefore related to the respective load state of the internal combustion engine.

The piston 20 thus throttles the pressure medium outflow from the outlet conduit 17 in relation to the load applied to the transmission and thus holds the pressure medium pressure in said outlet conduit in proportion to the spring force of the spring 22. ..

The amount of pressure medium pushed out by the end face 21 when the spring force increases is returned to the outflow conduit 17 via the conduit 25. In this case, the amount of the pressure medium is limited by the throttle 26 and the check valve 27.
Flows through and. When the spring force is reduced, the check valve 27 closes, so that the pressure medium is only transferred via the throttle 26 to the end face 21.
It flows back into the volume released from.

As a result, the piston 20 increases the pressure medium pressure in the outflow conduit 17 when the load increases, more quickly than when the piston decreases the pressure medium pressure when the load decreases.

The pressure created behind the preload valve 18 is defined in the conduit 28 by a torque feeler 19 mounted on the output shaft 2. The torque feeler throttles the pressure built up in the conduit 28 in relation to the load taken from the transmission. Since the torque feeler 19 is mounted on the output shaft 2, the pressure in the conduit 18 is primarily related to the load passed through the transmission, but especially to the transmission gear ratio. It is related.

If the pressure defined by the torque feeler 19 in the conduit 28 is higher than the pressure medium pressure set by the preload valve 18 against the outlet conduit 17, the preload valve 18 does not act. Outflow conduit 1
The pressure created in 7 corresponds to the pressure in conduit 28. That is, the pressure medium pressure formed in the outflow conduit 17 is always
It is defined by the downstream throttling element (preload valve 18 or torque feeler 19) that requires a higher pressure. Such a throttle element is the preload valve 18 when the gear ratio is low and the torque feeler 19 when the gear ratio is large.

In the illustrated embodiment, the torque feeler is configured as a torque pump. The torque pump blocks the outflow of pressure medium from the conduit 28 during a sudden torque shock, pushing the defined pressure medium volume back into the conduit. This pressure-medium volume flows into the pressure-medium conduits 8, 9 via the check valve 29, where said pressure-medium volume causes a sudden pressure increase in the cylinder piston units 6, 7. Due to the rapid pressure increase, the pressing force of the conical pulley pair against the transmission means increases in a very short time, which prevents the transmission from idling due to torque shock.

The conical pulley type continuously variable transmission shown in FIG. 2 is substantially the same as that shown in FIG. 1, but in the conical pulley type continuously variable transmission shown in FIG. The control of 30 is carried out via the proportional valve 31. This proportional valve controls the pressure from the pump 13 down to the pressure required to control the preload valve 30.

The control of the proportional valve 31 is in this case likewise carried out via the microprocessor 12.

Such an arrangement allows a more precise adjustment of the pressure medium pressure formed in the outlet conduit 17 in accordance with the actual load conditions of the transmission.

Thus, the invention is a convenient means for enabling pressure control in a conical pulley continuously variable transmission of the type mentioned at the outset.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 input shaft, 2 output shaft, 3,4 conical pulley pair, 5 transmission means, 6,7 cylinder piston unit, 8,9 pressure medium conduit, 10 4 control edge type spool, 11 adjusting device, 12 microprocessor, 13 Pump, 14 Reservoir, 15, 16 Outflow Portion, 17 Outflow Pipeline, 18 Preload Valve, 1
9 torque feeler, 20 piston, 21 end face, 22 spring, 23 cam transmission device, 24 accelerator pedal, 25 conduit, 26 throttle, 27 check valve, 28 conduit, 29 check valve, 30 preload valve, 31 proportional valve

Claims (9)

[Claims] 1. A conical pulley type continuously variable transmission, comprising two conical pulley pairs arranged on an input shaft and an output shaft,
And a transmission means for circulating between the pair of conical pulleys, each conical pulley being non-rotatably connected to a shaft supporting said conical pulleys, one cone for each shaft. The shaped pulley is fixed in position even in the axial direction.
The conical pulley of is configured as an axially slidable portion of an axially fixed cylinder piston unit, and for the purpose of pressing the transmission means to the cylinder piston unit and adjusting and maintaining the gear ratio, Pressure medium is supplied from a four-control-edge spool via a supply, said four-control-edge spool being adjustable by means of an adjusting device and an outlet for the charged pressure medium. An outlet conduit is connected to the outlet and at least one torque feeler is disposed in the outlet conduit, the torque feeler being one of the shafts of the transmission.
Is arranged in the torque transmission path of the shaft and influences the pressure medium pressure in the cylinder piston unit in relation to the load, the torque feeler being provided with an adjustable preload valve. In a serially connected manner, the preload valve additionally affecting the pressure medium pressure,
A torque feeler (19) is arranged on the output shaft (2) so that the preload valves (18, 30) are controlled in relation to the load applied to the transmission, so that when the load increases, the load A conical pulley type continuously variable transmission characterized in that the pressure medium outflow is reduced more than when it is reduced. 2. A preload valve (18, 30) is hydraulically placed in front of the torque feeler (19),
The conical pulley type continuously variable transmission according to claim 1. 3. The movement of the preload valve (18, 30) is adjusted against a resistance connected to the preload valve (18, 30), the resistance being increased when the load increases. The preload valve (18,
30. The conical pulley type continuously variable transmission according to claim 1, which enables the movement adjusting speed of 30). 4. The resistance is formed as a cylinder piston arrangement, the movable part (21) of which is the piston (20) of a preload valve (18).
The cylinder piston device is firmly connected to
It has a volume filled with a pressure medium, which volume is reduced when the load is increased and emptied via a fixed throttle (26) and a check valve (27) which then opens. 4. The conical pulleyless type according to claim 3, wherein the volume is expanded when the load is reduced and the pressure medium is filled only through the fixed throttle (26). Gearbox. 5. Evacuation or filling of the volume with pressure medium is carried out via at least one conduit (25), one end of which is
A pressure medium pressure is created in the outflow portion (17) of the four-controlled edge spool (10), at the other end of the conduit the check valve (27) and / or the stationary valve. 5. The conical pulley type continuously variable transmission according to claim 4, wherein a throttle (26) is arranged. 6. The load-related preload valve (1)
8. The cone according to claim 1, wherein the control of 8) is performed via a cam transmission (23), which cam transmission is connected to an accelerator pedal of an internal combustion engine acting as a drive. Shaped pulley type continuously variable transmission. 7. Control of said preload valve (30) is carried out by an electronic control unit (12, 31), said electronic control unit being detected by a sensor of an internal combustion engine acting as a drive unit. The conical pulley continuously variable transmission according to claim 1, wherein the control command is formed based on the data. 8. The electronic control device comprises a proportional valve (31), the preload valve (30) being operable by a hydraulic pressure which can be set by the proportional valve (31). Item 7. A conical pulley type continuously variable transmission according to Item 7. 9. A torque feeler (19) is formed as a torque pump, and a control valve is arranged in front of the torque feeler (19) and the cylinder piston unit (6, 7). (10, 18, 3
0) to a bypass conduit, which has a check valve (29), through which the torque feeder (19) passes during the sudden torque increase.
The conical pulley type continuously variable transmission according to claim 1, wherein a pressure medium flows from the cylinder piston unit (6, 7) into the cylinder piston unit (6, 7).